Merge branch 'feature/reddit-channel' into 'master'

Relay subreddit posts to the #reddit channel

See merge request python-discord/projects/bot!23

5 files changed, 333 insertions, 0 deletions

diff --git a/bot/__main__.py b/bot/__main__.py
index c5c8b8909..a2c10476c 100644
--- a/bot/__main__.py
+++ b/bot/__main__.py
@@ -64,6 +64,7 @@ bot.load_extension("bot.cogs.hiphopify")
 bot.load_extension("bot.cogs.information")
 bot.load_extension("bot.cogs.moderation")
 bot.load_extension("bot.cogs.off_topic_names")
+bot.load_extension("bot.cogs.reddit")
 bot.load_extension("bot.cogs.snakes")
 bot.load_extension("bot.cogs.snekbox")
 bot.load_extension("bot.cogs.tags")
diff --git a/bot/cogs/reddit.py b/bot/cogs/reddit.py
new file mode 100644
index 000000000..952fa4682
--- /dev/null
+++ b/bot/cogs/reddit.py
@@ -0,0 +1,291 @@
+import asyncio
+import logging
+import random
+import textwrap
+from datetime import datetime, timedelta
+
+from discord import Colour, Embed, TextChannel
+from discord.ext.commands import Bot, Context, group
+
+from bot.constants import Channels, ERROR_REPLIES, Reddit as RedditConfig, Roles
+from bot.converters import Subreddit
+from bot.decorators import with_role
+from bot.pagination import LinePaginator
+
+log = logging.getLogger(__name__)
+
+
+class Reddit:
+    """
+    Track subreddit posts and show detailed statistics about them.
+    """
+
+    HEADERS = {"User-Agent": "Discord Bot: PythonDiscord (https://pythondiscord.com/)"}
+    URL = "https://www.reddit.com"
+
+    def __init__(self, bot: Bot):
+        self.bot = bot
+
+        self.reddit_channel = None
+
+        self.prev_lengths = {}
+        self.last_ids = {}
+
+    async def fetch_posts(self, route: str, *, amount: int = 25, params=None):
+        """
+        A helper method to fetch a certain amount of Reddit posts at a given route.
+        """
+
+        # Reddit's JSON responses only provide 25 posts at most.
+        if not 25 >= amount > 0:
+            raise ValueError("Invalid amount of subreddit posts requested.")
+
+        if params is None:
+            params = {}
+
+        response = await self.bot.http_session.get(
+            url=f"{self.URL}/{route}.json",
+            headers=self.HEADERS,
+            params=params
+        )
+
+        content = await response.json()
+        posts = content["data"]["children"]
+
+        return posts[:amount]
+
+    async def send_top_posts(self, channel: TextChannel, subreddit: Subreddit, content=None, time="all"):
+        """
+        Create an embed for the top posts, then send it in a given TextChannel.
+        """
+
+        # Create the new spicy embed.
+        embed = Embed()
+        embed.description = ""
+
+        # Get the posts
+        posts = await self.fetch_posts(
+            route=f"{subreddit}/top",
+            amount=5,
+            params={
+                "t": time
+            }
+        )
+
+        if not posts:
+            embed.title = random.choice(ERROR_REPLIES)
+            embed.colour = Colour.red()
+            embed.description = (
+                "Sorry! We couldn't find any posts from that subreddit. "
+                "If this problem persists, please let us know."
+            )
+
+            return await channel.send(
+                embed=embed
+            )
+
+        for post in posts:
+            data = post["data"]
+
+            text = data["selftext"]
+            if text:
+                text = textwrap.shorten(text, width=128, placeholder="...")
+                text += "\n"  # Add newline to separate embed info
+
+            ups = data["ups"]
+            comments = data["num_comments"]
+            author = data["author"]
+
+            title = textwrap.shorten(data["title"], width=64, placeholder="...")
+            link = self.URL + data["permalink"]
+
+            embed.description += (
+                f"[**{title}**]({link})\n"
+                f"{text}"
+                f"| {ups} upvotes | {comments} comments | u/{author} | {subreddit} |\n\n"
+            )
+
+        embed.colour = Colour.blurple()
+
+        return await channel.send(
+            content=content,
+            embed=embed
+        )
+
+    async def poll_new_posts(self):
+        """
+        Periodically search for new subreddit posts.
+        """
+
+        while True:
+            await asyncio.sleep(RedditConfig.request_delay)
+
+            for subreddit in RedditConfig.subreddits:
+                # Make a HEAD request to the subreddit
+                head_response = await self.bot.http_session.head(
+                    url=f"{self.URL}/{subreddit}/new.rss",
+                    headers=self.HEADERS
+                )
+
+                content_length = head_response.headers["content-length"]
+
+                # If the content is the same size as before, assume there's no new posts.
+                if content_length == self.prev_lengths.get(subreddit, None):
+                    continue
+
+                self.prev_lengths[subreddit] = content_length
+
+                # Now we can actually fetch the new data
+                posts = await self.fetch_posts(f"{subreddit}/new")
+                new_posts = []
+
+                # Only show new posts if we've checked before.
+                if subreddit in self.last_ids:
+                    for post in posts:
+                        data = post["data"]
+
+                        # Convert the ID to an integer for easy comparison.
+                        int_id = int(data["id"], 36)
+
+                        # If we've already seen this post, finish checking
+                        if int_id <= self.last_ids[subreddit]:
+                            break
+
+                        embed_data = {
+                            "title": textwrap.shorten(data["title"], width=64, placeholder="..."),
+                            "text": textwrap.shorten(data["selftext"], width=128, placeholder="..."),
+                            "url": self.URL + data["permalink"],
+                            "author": data["author"]
+                        }
+
+                        new_posts.append(embed_data)
+
+                self.last_ids[subreddit] = int(posts[0]["data"]["id"], 36)
+
+                # Send all of the new posts as spicy embeds
+                for data in new_posts:
+                    embed = Embed()
+
+                    embed.title = data["title"]
+                    embed.url = data["url"]
+                    embed.description = data["text"]
+                    embed.set_footer(text=f"Posted by u/{data['author']} in {subreddit}")
+                    embed.colour = Colour.blurple()
+
+                    await self.reddit_channel.send(embed=embed)
+
+                log.trace(f"Sent {len(new_posts)} new {subreddit} posts to channel {self.reddit_channel.id}.")
+
+    async def poll_top_weekly_posts(self):
+        """
+        Post a summary of the top posts every week.
+        """
+
+        while True:
+            now = datetime.utcnow()
+
+            # Calculate the amount of seconds until midnight next monday.
+            monday = now + timedelta(days=7 - now.weekday())
+            monday = monday.replace(hour=0, minute=0, second=0)
+            until_monday = (monday - now).total_seconds()
+
+            await asyncio.sleep(until_monday)
+
+            for subreddit in RedditConfig.subreddits:
+                # Send and pin the new weekly posts.
+                message = await self.send_top_posts(
+                    channel=self.reddit_channel,
+                    subreddit=subreddit,
+                    content=f"This week's top {subreddit} posts have arrived!",
+                    time="week"
+                )
+
+                if subreddit.lower() == "r/python":
+                    # Remove the oldest pins so that only 5 remain at most.
+                    pins = await self.reddit_channel.pins()
+
+                    while len(pins) >= 5:
+                        await pins[-1].unpin()
+                        del pins[-1]
+
+                    await message.pin()
+
+    @group(name="reddit", invoke_without_command=True)
+    async def reddit_group(self, ctx: Context):
+        """
+        View the top posts from various subreddits.
+        """
+
+        await ctx.invoke(self.bot.get_command("help"), "reddit")
+
+    @reddit_group.command(name="top")
+    async def top_command(self, ctx: Context, subreddit: Subreddit = "r/Python"):
+        """
+        Send the top posts of all time from a given subreddit.
+        """
+
+        await self.send_top_posts(
+            channel=ctx.channel,
+            subreddit=subreddit,
+            content=f"Here are the top {subreddit} posts of all time!",
+            time="all"
+        )
+
+    @reddit_group.command(name="daily")
+    async def daily_command(self, ctx: Context, subreddit: Subreddit = "r/Python"):
+        """
+        Send the top posts of today from a given subreddit.
+        """
+
+        await self.send_top_posts(
+            channel=ctx.channel,
+            subreddit=subreddit,
+            content=f"Here are today's top {subreddit} posts!",
+            time="day"
+        )
+
+    @reddit_group.command(name="weekly")
+    async def weekly_command(self, ctx: Context, subreddit: Subreddit = "r/Python"):
+        """
+        Send the top posts of this week from a given subreddit.
+        """
+
+        await self.send_top_posts(
+            channel=ctx.channel,
+            subreddit=subreddit,
+            content=f"Here are this week's top {subreddit} posts!",
+            time="week"
+        )
+
+    @with_role(Roles.owner, Roles.admin, Roles.moderator, Roles.helpers)
+    @reddit_group.command(name="subreddits", aliases=("subs",))
+    async def subreddits_command(self, ctx: Context):
+        """
+        Send a paginated embed of all the subreddits we're relaying.
+        """
+
+        embed = Embed()
+        embed.title = "Relayed subreddits."
+        embed.colour = Colour.blurple()
+
+        await LinePaginator.paginate(
+            RedditConfig.subreddits,
+            ctx, embed,
+            footer_text="Use the reddit commands along with these to view their posts.",
+            empty=False,
+            max_lines=15
+        )
+
+    async def on_ready(self):
+        self.reddit_channel = self.bot.get_channel(Channels.reddit)
+
+        if self.reddit_channel is not None:
+            self.bot.loop.create_task(self.poll_new_posts())
+            self.bot.loop.create_task(self.poll_top_weekly_posts())
+        else:
+            log.warning("Couldn't locate a channel for subreddit relaying.")
+
+
+def setup(bot):
+    bot.add_cog(Reddit(bot))
+    log.info("Cog loaded: Reddit")
diff --git a/bot/constants.py b/bot/constants.py
index 756c03027..5e1dc1e39 100644
--- a/bot/constants.py
+++ b/bot/constants.py
@@ -321,6 +321,7 @@ class Channels(metaclass=YAMLGetter):
     off_topic_2: int
     off_topic_3: int
     python: int
+    reddit: int
     verification: int
 
 
@@ -407,6 +408,13 @@ class URLs(metaclass=YAMLGetter):
     paste_service: str
 
 
+class Reddit(metaclass=YAMLGetter):
+    section = "reddit"
+
+    request_delay: int
+    subreddits: list
+
+
 class AntiSpam(metaclass=YAMLGetter):
     section = 'anti_spam'
 
diff --git a/bot/converters.py b/bot/converters.py
index f18b2f6c7..3def4b07a 100644
--- a/bot/converters.py
+++ b/bot/converters.py
@@ -172,3 +172,29 @@ class InfractionSearchQuery(Converter):
         except Exception:
             return arg
         return user or arg
+
+
+class Subreddit(Converter):
+    """
+    Forces a string to begin with "r/" and checks if it's a valid subreddit.
+    """
+
+    @staticmethod
+    async def convert(ctx, sub: str):
+        sub = sub.lower()
+
+        if not sub.startswith("r/"):
+            sub = f"r/{sub}"
+
+        resp = await ctx.bot.http_session.get(
+            "https://www.reddit.com/subreddits/search.json",
+            params={"q": sub}
+        )
+
+        json = await resp.json()
+        if not json["data"]["children"]:
+            raise BadArgument(
+                f"The subreddit `{sub}` either doesn't exist, or it has no posts."
+            )
+
+        return sub
diff --git a/config-default.yml b/config-default.yml
index 415c1fcdf..fd0e33633 100644
--- a/config-default.yml
+++ b/config-default.yml
@@ -96,6 +96,7 @@ guild:
         off_topic_1:                      463035241142026251
         off_topic_2:                      463035268514185226
         python:                           267624335836053506
+        reddit:                           458224812528238616
         staff_lounge:      &STAFF_LOUNGE  464905259261755392
         verification:                     352442727016693763
 
@@ -291,3 +292,9 @@ anti_spam:
         role_mentions:
             interval: 10
             max: 3
+
+
+reddit:
+    request_delay: 60
+    subreddits:
+        - 'r/Python'